Addressing modes
- In immediate addressing, the operand field contains the data itself.
- In register direct addressing, the operand field contains the address of a datapath register in which the data resides.
- In register-indirect addressing, the operand field contains the address of a register, which in turn contains the address of a memory location in which the data resides.
- In direct addressing, the operand field contains the address of a memory location in which the data resides.
- In indirect addressing, the operand field contains the address of a memory location, which in turn contains the address of a memory location in which the data resides.
- Figure 2.6 shows a (trivial) instruction set with 4 data transfer instructions, 2 arithmetic instructions, and 1 branch instruction, for a hypothetical processor.
- Figure 2.7(a) shows a program, written in C, that adds the numbers 1 through 10. Figure 2.7(b) shows that same program written in assembly language using the given instruction set.
